1. Field of Invention
This invention relates to the field of image stabilization in the reproduction of remotely-sensed images.
2. Description of Prior Art
Image stabilization is an important problem in many image acquisition situations. For example, without image stabilization, the picture transmitted by a TV cameraman having a remote unit mounted on his shoulder will wobble when reproduced if, when the original image was acquired, the cameraman was jostled about by a crowd during a riot or if he was using a telephone lens. Likewise, live TV or video tape images produced by a helicopter or airplane-mounted TV camera require similar stabilization. Similarly, an earth or astronomical image acquired by a remote sensor mounted in an orbiting earth satellite becomes unstable if, during image acquisition, the satellite is, for some reason, perturbed from its instantaneous nominal attitude.
In the satellite case (for example, in the production of accurately detailed earth-resources maps), a method does exist for image stabilization. Transmitted to the ground station along with the data acquired from the satellite sensor are signals generated by an inertial platform or similar device which senses attitude perturbations from the norm. In this state-of-the-art method the perturbation data is digitized and, by means of a computer, this digital data is caused to adjust the data from the satellite (also digitized), representing the instantaneous nominal scan direction.
Because of the high image resolution and resultant large-volume data acquisition and transmission currently realizable in modern satellite-borne detector systems, and the rather complex matrix multiplication computer manipulations required to make the necessary adjustment in data values, this state-of-the-art method is marginally practical at best and impossible to implement in real time.
Obviously such a method is totally impractical in the case of ordinary live TV or video tape surveillance of a scene by a cameraman on the ground or in a helicopter.